Flexible medical device for clot removal from small vessels

Abstract

A medical device and method of applying said medical device to deliver drugs and to remove thrombus or soft tissue clots from vascular or other lumens in a patient is presented. The medical device generally comprises an elongated tubular delivery member having a proximal portion and a distal portion that differ in rigidity and a leak-free connector that is in contact with the proximal portion of the delivery member and is compatible for use with fibrinolytic agents and application of a vacuum. The delivery member includes a metal core made out of multiple shaped-wire strands and a polymer overlay disposed about the core. The wire strands, which have both an A-side and a B-side, are helically wound to form a polygonal shaped lumen whose inner diameter is defined by the A-side of the strands.

1. A medical device for clot removal from small vessels by fibrinolytic infusion or vacuum retrieval, the device comprising:
 an elongated tubular delivery member having a proximal portion and a distal portion, the delivery member comprising a metal core of multiple shaped-wire strands having an A-side and a B-side, the wire strands helically wound to form a lumen with an inner diameter defined by the A-side of the strands and a polymer overlay disposed about the metal core; the proximal portion and distal portion being different in their predetermined degree of rigidity; and 
 a leak-free connector in contact with the proximal portion of the delivery member; the connector being compatible for use with fibrinolytic infusion and vacuum retrieval; 
 wherein the helically wound wire strands form a first polygon defined by the B-side of the strands and a second polygon defined by the A-side of the strands; the second polygon defining the shape of the lumen. 
 
     
     
       2. The device of  claim 1 , wherein the first polygon inscribes a first circle having a radius, R 1 , and the second polygon circumscribes a second circle having radius, R 2 ;
 wherein the difference in magnitude between R 1  and R 2  is about equal to the thickness of the wire strands. 
 
     
     
       3. The device of  claim 2 , wherein the ratio of the area (A 1 ) of the first polygon to the area (A 2 ) of the second polygon is about equal to the quotient of:
   [( R   1 ) 2 ·cos 2 (π/ N )]/( R   2 ) 2 ,
 
 
       where N is the number of wire strands. 
     
     
       4. The device of  claim 1 , wherein the difference in rigidity of the proximal and distal portions of the delivery member results from a variation in one of the wall thickness of the metal core, the hardness of the overlay, and a combination thereof. 
     
     
       5. The device of  claim 1 , wherein the shape of the wire strands that form the metal core is selected as one from the group of half round shaped D-wire, less than half round shaped D-wire, pie angle shaped wire with greater than about a 100° degree angle, triangular shaped wire having an obtuse angle, rectangular shaped wire, square shaped wire, flat shaped wire, crescent shaped wire, and combinations thereof. 
     
     
       6. The device of  claim 1 , wherein the hollow metal core has an inside diameter that is less than about 1.25 mm and an outside diameter that is greater than about 0.30 mm. 
     
     
       7. The device of  claim 6 , wherein the ratio of the inside diameter to the outside diameter is greater than about 1.5. 
     
     
       8. The device of  claim 1 , wherein the metal core is made up of at least 5 shaped-wire strands. 
     
     
       9. The device of  claim 1 , wherein the hollow metal core comprises two layers of helically wound shaped-wire strands; the second layer being disposed about the first layer. 
     
     
       10. The device of  claim 1 , wherein the polymer overlay is one selected from the group of a coated material, an extruded material, and a shrink tubing material; with the composition of the material being one selected from the group of fluoropolymers, hyrdrophilic elastomers, polyolefins, and combinations or mixtures thereof. 
     
     
       11. The device of  claim 1 , wherein the leak-free connector is one selected from the group of a Luer-lock fitting and Luer-Slip fitting. 
     
     
       12. The device of  claim 4 , wherein the variation in wall thickness of the core results from a grinding operation being performed on the outer diameter of the core's distal portion. 
     
     
       13. The device of  claim 4 , wherein the variation in wall thickness of the hollow core results from using at least one different core for the proximal portion and the distal portion that have substantially similar inner diameters, but different outer diameters;
 wherein the distal end of the core used in the proximal portion of the delivery member and the proximal end of the core used in the distal portion of the delivery member are in contact with one another such that their inner diameters engage one another. 
 
     
     
       14. The device of  claim 1 , wherein the rigidity of the proximal portion is greater than the rigidity of the distal portion. 
     
     
       15. The device of  claim 1 , wherein the distal portion further comprises a distal end in which the inner diameter of the delivery member is tapered to contact and retrievably receive a guide wire. 
     
     
       16. The device of  claim 1 , wherein the multiple shaped-wire strands are helically wound with a pitch angle (α) between about 25 to 77 degrees. 
     
     
       17. The device of  claim 1 , wherein the distal portion of the delivery member further comprises a radiopaque material to enhance visibility during fluoroscopy; the radiopaque material being one selected from the group of gold, platinum, iridium, palladium, rhodium, and a mixture thereof. 
     
     
       18. The device of  claim 1 , wherein the wire strands are each angled in the same direction relative to a longitudinal axis defined by the lumen. 
     
     
       19. The device of  claim 18 , wherein the wire strands are parallel to each other. 
     
     
       20. A medical device for clot removal from small vessels by fibrinolytic infusion or vacuum retrieval, the device comprising:
 an elongated tubular delivery member having a proximal portion and a distal portion, the delivery member comprising a metal core of multiple non-braided shaped-wire strands having an A-side and a B-side, the wire strands helically wound to form a lumen with an inner diameter defined by the A-side of the strands and a polymer overlay disposed about the metal core; the proximal portion and distal portion being different in their predetermined degree of rigidity; and 
 a leak-free connector in contact with the proximal portion of the delivery member; the connector being compatible for use with fibrinolytic infusion and vacuum retrieval; 
 wherein the helically wound wire strands form a first polygon defined by the B-side of the strands and a second polygon defined by the A-side of the strands; the second polygon defining the shape of the lumen.